Their goal is development and sustenance of the business, thats not their product unless they're Berkshire. They can only make products that can be sold profitably if they make products that work. All the marketing in the world can only do so much (not saying it cannot salvage at all) if a drug just doesn't work. And a CEO should know as best as any human can know whether a drug they will be spending billions on has a good chance of working or not. In the end, that's the most important decision for a pharma company and a CEO cannot just outsource it to some other experts. From where I can see that is the reason pharma companies don't deliver as much value as they should be given the investments they make.
Their goal is development and sustenance of the business, thats not their product
That's why I put "product" in quotes. The CEO's concern is the business. Domain experts handle the tactical decisions.
a CEO cannot just outsource it to some other experts
I'm sorry but that is precisely what happens in big business all over the world. Call it "expert guidance" if you want, but if you really think the CEO is solely responsible for making domain decisions, as well as all the business development ones, you're misinformed. They will have views, but those will almost certainly come from the business end, not the domain end.
Apart from anything else, domain knowledge can change so fast, a CEO can't be expected to stay at the bleeding edge and manage the business.
